It does mean much cause this is Disney. They're not gonna make a game were your character is actually some evil mofo destroying lives or worlds.
Xehanort exclaims that "swore I'd survive to see what lies beyond the great keyblade war" before taking Terras body. He wouldn't be so desperate to see it if he had already. Plus the war predates the very current kh universe, there's no way Xehanorts seen it.